Field
Embodiments described generally relate to packoff seals and processes for using same.
Description of the Related Art
Oil and gas well servicing can involve inserting a tool into the wellbore to analyze geological formations around the wellbore, gather information about the hydrocarbon reservoir, determine the integrity of the wellbore, or for other reasons. The tool can be connected to a cable that is either a wireline, which has electrical conductors for sending and/or receiving data to the tool, or a slickline which does not include electrical conductors. These cables are typically connected to a winch at the surface and are used to lower and raise the tool in the wellbore.
As a safety precaution, a packoff assembly can be installed on the wellhead to assist in control of well pressure. The packoff assembly typically can include dual packoff seals for sealing around the cable while the tool is in the wellbore and while the winch lowers and raises the tool. The packoff assembly can be manually or remotely controlled using hydraulic pressure or can be activated automatically based on well pressure.
Conventional packoff seals include a piece of rubber molded into a generally cylindrical shape having a bore disposed therethrough along a central longitudinal axis thereof, which allows a cable to pass through the packoff seal. Often, heat and vibration generated after a couple of well servicing operations can cause deterioration of the rubber in the packoff seal leading to frequent replacement of conventional packoff seals.
There is a need, therefore, for packoff seals having improved resistance to deterioration during well servicing operations.